The seat and the "shim" are the same thing. Gimme a minute and I'll get pictures.

 

You don't have to do that. Ill just watch a video on it.

 

I'm in the middle of pulling it all apart. Easy to get a pic.

 

Stock stack



What comes from supertech. (Singles in the photo. Doubles include another smaller spring that fits inside)

 

So that black thing in the second photo is the shim that goes under the retainer on the right?

 

No that's a spring seat.

Managed to toast another lifter. One of the cam lobes has some marking on it that I believe did this. Not sure if I overlooked it or whatever. Getting another lifter ordered.

**** this ****.

 

This is the stock shim:



OEM it's primarily there to keep the spring from wearing direction on the aluminum. With the Supertech springs, you're supposed to keep it, although now it's just a .005" spacer, because instead of the spring going on top you have this:



That's the ST spring seat. On top of that go the springs:



That's a set of the heavy doubles. On top of those go the top mount (not sure what that's called), and the two keepers go inside that. The valve stem sticks up through the hole in the center, and the grooves on the stem engage with ridges in the keepers to lock it all together.

The .005" shim doesn't sound like much, but it's adding preload to the spring. Preload is important -- I measured my exhaust manifold pressure at 350 kpa at one point. That's 50 psi pressing on the top of the exhaust valve, and since the valve has an area of a bit more than a square inch, it means that there's 50+ pounds of force trying to shove the valve open during the intake stroke. So you need a bunch of preload to keep the valve up against the seat.

--Ian

(ack, stupid web site coughed up a hairball when I was editing this to add the bit about preload)

 

FTFY

 

PM me. My guest room is occupied next week, but the couch is available. Or if you just want a place to park where you can walk to the lakes without worrying about it. I actually need to go to SF soon anyway, so I can visit you there if you want.

 

New cam has a chip on the lobe. Might also be junk. Opinions?

 

They call him "the valvetrain destroyer"

 

This is the 3rd cam I've looked at.

Reading around says that as long as its not a high spot its ok to run.

 

Stone off the sharp edges, first.

 

correct

 

Cam looks fine to run.

 

This. Don't want a small crack in that spot where it's chipped to spread and break the cam even more. Grind that chip out and move on.

 

so just hit the edges with a diamond stone or something? Still waiting to hear back about getting a new lifter from miataroadster.

 

If you have a bench grinder a 120 grit Silicon Carbide wheel will take the sharp edges off easily without worrying about too much. Just keep it away from the journals.

 

Do not have that. Also that+bench grinder+cam+aidan = trashed cam

 

I forgot which thread this was.... carry on. Did you use my soda straw method (actually, not mine...)?